Comparison of Vitamin D Levels in Premature Infants with and without Retinopathy of Prematurity

Background: Retinopathy of prematurity (RoP) is a cause of newborn blindness. Several predisposing factors have been reported to contribute to the disease process. The current study aimed to compare serum vitamin D levels in infants with and without RoP. Methods: This case-control study was conducted on 154 very low birth weight (VLBW) infants admitted to Ghaem hospital, Mashhad, Iran, during 2016-2019. Retinal examination for RoP was done at the 32nd week of pregnancy and vitamin D level was determined using the infants' first-day serum samples. A researcher-made questionnaire including maternal, infant, laboratory, and retinal examination information was used as the data collection tool. Results: Out of 154 infants in the study, 56 (36.4%) were normal while 98 (63.6%) had RoP. Based on the severity of retinopathy, 43 infants (43.9%) were at stage I, 48 (49%) at stage II, and 7 (7.1%) at stage III. Significant differences in neonatal (P< 0.001) and maternal (P = 0.015) vitamin D levels, first and fifth minute Apgar scores (P= 0.034 and P = 0.001, respectively), and weight (P = 0.014) were found between the infants with and without RoP. Conclusion: The incidence of RoP was higher in infants with lower gestational age, lower birth weight, low first and fifth minutes Apgar scores, and male sex. Low serum levels of vitamin D in premature infants and their mothers were associated with incidence of RoP. The higher the stage of RoP, the greater was the severity of vitamin D deficiency. Thus, controlling the maternal vitamin D level during pregnancy, consumption of vitamin D supplements, and investigation of serum vitamin D levels in premature infants are recommended. Early correction of vitamin D deficiency may lead to reduction of RoP.